Sewing machine automatic work steering mechanisms



Oct. 14, 1969; R. M. KAPLAN ETAL 3,472,187

SEWING MACHINE AUTOMATIC WORK STEERING MECHANISMS Filed necfi ls 1967 2Sheets-Shea 1 Fig.l.

20 6| INVENTORS SROFIOIU M. Kaplan And Witness 62 55 mnley J. Ketterer-fia%lind-n ATTORNEY Oct. 14, 1969 R. M. KAPLAN ETAL SEWING MACHINEAUTOMATIC WORK STEERING MECHANISMS Filed D60. 19, 1967 2 Sheets-Sheet 2INVENTORS Ronald M. Koplan And v Stanley J Ketterer 64 BY I W 4.4;ATTORNEY United States Patent 3,472,187 SEWING MACHINE AUTOMATIC WORKSTEERING MECHANISMS Ronald M. Kaplau, Cedar Grove, and Stanley J.

Ketterer, Morris Plains, N.J., assignors to The Singer Company, NewYork, N.Y., a corporation of New Jersey Filed Dec. 19, 1967, Ser. No.691,892 Int. Cl. Db 27/12 U.S. Cl. 112212 9 Claims ABSTRACT OF THEDISCLOSURE An automatic work steering mechanism for a sewing machine isdisclosed including means connected to a servomechanism for sensing theedge of work piece on a work supporting surface of a sewing machine tosignal the servomechanism when the edge of the work piece deviates froma predetermined line so that the servomechanism can operate means formoving the axis of a feed wheel to steer the work back into the line.

BACKGROUND OF THE INVENTION Field of the invention The invention relatesto sewing machine work steering mechanisms.

Description of the prior art In many kinds of sewing operations, it isdiflicult to maintain a uniform margin between a line of stitches inwork and the edge of the work. Maintaining a uniform margin isespecially diflicult in post type sewing machines used for leathersewing because of the characteristics of the work and the small area ofwork supporting surface in the Vicinity of the stitching point. Formerwork steering mechanisms have often not been sensitive enough, and havebeen expensive employing complicated mechanical mechanisms andphotoelectric sensing devices.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is arear elevational view of a sewing machine incorporating the improvedautomatic work steering mechanism of the invention;

FIG. 2 is an enlarged detail view of the stitching area of the sewingmachine of FIG. 1;

FIG. 3 is a head end elevational view partly in section of the stitchingarea of FIG. 2; and

FIG. 4 is a cross sectional view taken substantially along the line 44in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawings,in FIG. 1 the improved automatic work steering mechanism of theinvention is shown embodied in a sewing machine having a frame includinga base 11, a post 12 rising from one end of the base with a worksupporting surface 13 on the top of the post, a standard 14 rising fromthe other end of the base,

a bracket arm 15 at the topof the standard overhanging the base, and asewing head 16 on the free end of the bracket arm above the worksupporting surface of the post. As shown in FIG. '2, a conventionalneedle bar 17 is mounted in the sewing head for endwise reciprocation. Aneedle 18 is connected to the end of the needle bar to form stitches 19in work piece 20 on the work supporting surface of the post.

Also mounted in the sewing head is a presser bar 21. As shown in FIG. 3,the presser bar has a coaxial bore 22 which houses a compression coilspring 23 and encompasses the lower extremity of a rod 24 mounted in thesewing head. The compression coil spring is sandwiched between the endof the rod and the bottom of the bore to bias the presser bardownwardly. An arcuate segment 25 is formed at the bottom of the presserbar, and an arcuate slideway 26 is formed in the arcuate segment. Thearcuate slideway has an interior portion 27, and a communicatingexterior portion 28 formed by two opposed ledges 29 at the bottom of thearcuate segment. The interior portion of the arcuate slideway is widerthan the exterior portion giving the arcuate slideway an overallT-shaped cross section.

Mounted in the arcuate slideway at the bottom of the presser bar is anarcuate slide block 30. The arcuate slide block has a head portion 31and a neck portion 32 giving it a T-shaped cross section complementaryto the T-shaped cross section of the arcuate slideway. The head portionof the arcuate slide block seats in the interior portion of the arcuateslideway and the neck portion seats in the exterior portion of thearcuate slideway. The neck portion of the arcuate slide block rises fromthe top of a block 33 which has a lateral arm 34. The lateral arm has aspherical bearing 35 formed at an intermediate portion and a head 36 onthe free end. A downwardly extending rod 37 having a coaxial bore 38 ismounted in a bore 39 in the block by a setscrew 40, and a downwardlyextending medial boss 41 having a semicircular cross section is formedon the bottom of the block.

Mounted on the rod which extends downwardly from the block is a collar42. The collar is connected to the downwardly extending rod by asetscrew 43 and has a groove 44 formed in the top with an inversetrapezoidal cross section mating with the boss 41 on the bottom of theblock. A lateral flange 45 extends from the bottom of the collar. Alsomounted on the rod is a second collar 46. The second collar also has alateral flange 47 extending from the bottom and in the same direction asthe lateral flange on the first collar. In addition, the second collarhas a counterbore 48 in the bottom which houses a compression coilspring 49. The compression coil spring bears againsta flange 50 on thebottom of a pin 51 which is mounted 1n the bore 38 in the rod by asetscrew 52 to bias the second collar upwardly. I

Connected to the second collar by a screw 53 15 an extension 54 of abracket 55. The extension is sandwiched between the flanges 45 and 47 ofthe two collars. The flanges prevent pivotal movement of the bracketabout the screw 53, and the compression coil spring 49 biases theextension against the uppermost flange via the lowermost flange. A shaft56 in the form of a screw having a head 57 is connected to the bracketby two nuts 58 and 59 with the axis of the shaft canted. A pulley 60 anda feed wheel 61 are freely mounted on the shaft, the feed wheel beingintegral with the pulley. The feed wheel has a knurled circumferentialsurface 6 2 for feeding the work piece on the work supporting surface ofthe post. Rotation is imparted to the feed wheel by a belt 63 whichengages the pulley. The other end of the belt engages means in thesewing head which are not shown. Reference may be had to the UnitedStates Patent No. 2,678,010, May 1], 1954, for a more detaileddisclosure of this feed Wheel drive. The bracket is stabilized by a rod64 extending upwardly from the bracket to the means in the sewing head.

In order to sense the edge of the work; a sensing foot 65 having a toe66, a heel 67, and an upwardly extending leg 68 is connected to adepending lever 69 on a bracket 70 connected to the sewing head. The toeof the sensing foot contacts the edge of the work. The sensing foot ispivotally connected to the depending lever by a pivot screw 71 whichextends through a longitudinal clearance slot 72 in the upwardlyextending leg. The depending lever has an alternative hole 73 for thepivot screw 71 for adjustment purposes. The longitudinal slot in theupwardly extending leg enables the sensing foot to be manually liftedoff of the work supporting surface of the post. The depending lever isconnected to the bracket by a screw 74, and the bracket is connected tothe sewing head by two screws 75 of which one is shown in FIG. 2. Thedepending lever is sandwiched between a stop 76 on a plate 77 on thebottom of the bracket and the free arm of a lever 78 connected to thebracket by 'a screw 79. The stop and the lever provide an adjustmentfeature for the lateral position of the toe of the sensing foot on thework supporting surface of the post by fixing the angular orientation ofthe depending lever about its mounting screw 74.

Mounted on the bracket 70 is a controlled potentiometer 80 having ashaft 81. A crank arm 82 is clamped to the end of the shaft by a screw83. The crank arm is biased in a clockwise direction by a torsion spring84 mounted on the shaft. A link 85 having a longitudinal clearance slot86 is pivotally connected to the free end of the crank arm by a pivotscrew 87, and a second link 88 is pivotally connected to the heel of thesensing foot by a pivot screw 89. The two links are linearly connectedby two screws 90 and 91 which extend through the longitudinal clearanceslot in the first link. The two screws keep the two links in line, andthe longitudinal slot 86 in conjunction with the longitudinal slot 72 inthe upwardly extending leg enable the sensing foot to be manually liftedoff of the work supporting surface of the post. The torsion spring 84 onthe shaft of the potentiometer biases the toe of the sensing footagainst the edge of the work.

The controlled potentiometer is connected to an amplifier 92 by anelectrical cord 93, and the amplifier in turn is connected to aservomechanism in the form of a servomotor 94 by an electrical cord 95.The amplifier has a power cord 96 for connection to a conventionalelectric outlet which is not shown. The servomotor has a rotor shaft 97and is mounted on a bracket 98 which is connected to the standard of thesewing machine by two screws 99 with the rotor shaft in a substantiallyvertical position. A crank arm 100 is clamped on the end of the rotorshaft by a screw 101, and a connecting rod 102 is pivotally connected tothe free end of the crank arm by a pivot screw 103. The other end of theconnecting rod has a strap 104 which embraces the spherical bearing 35on the arm extending laterally from the block which is connected to thebottom of the presser bar.

In operation, the feed wheel 61 feeds the work 20 across the worksupporting surface of the post while the needle tforms stitches 19 inthe work. The toe 66 of the sensing foot 65 is biased against the edgeof the work by the torsion spring 84 on the shaft of the controlledpotentiometer 80. When the edge of the work moves away from the toe ofthe sensing foot thus shortening the margin between the line of stitchesand the edge of the work, the toe of the sensing foot continues tocontact the edge of the work because of the action of the torsionspring. In continuing to contact the edge of the work as the edge of thework moves away from the toe of the sensing foot, the sensing footcauses the crank arm 82 of the controlled potentiometer to turn throughmovement of the two links 88 and 85 connected between the sensing footand the crank arm. Turning of the crank arm causes the controlledpotentiometer to send an electrical signal to the servomotor 94 throughthe amplifier 92. The signal causes the servomotor to turn its crank arm99 to pull the connecting rod 102 towards the standard end of the sewingmachine. Rearward movement of the connecting rod causes the arcuateslide block 30 to slide in the arcuate slideway 26 in the bottom of thepresser bar to turn the feed wheel 61 to the right as viewed from thefront of the sewing machine. When the feed wheel is turned to the right,it feeds the work so that the edge of the work moves back towards thetoe of the sensing foot to restore equilibrium with the edge of the workon a predetermined line as set by the initial position of the toe of thesensing foot. When the equilibrium position is reached, the controlledpotentiometer causes the servomotor 94 to return the feed wheel 61 toits normal straightened position. It must be appreciated that theautomatic work steering mechanism is very sensitive and that the edge ofthe work can never deviate very far from the predetermined line. Theangular orientation of the depending lever 69 on the bracket 70connected to the sewing head sets the predetermined line represented bythe toe 66 of the sensing foot. The angular orientation of the dependinglever can be adjusted by the stop 76 and the lever 78 on the bracket 70to adjust the predetermined line. The longitudinal slots 72 and 86 inthe upwardly extending leg 68 of the sensing foot and the link enablethe sensing foot to be manually lifted off of the work supportingsurface 13 of the post.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made by way of example andthat numerous changes in the details of construction and the combinationand arrangement of parts can be resorted to without departing from thespirit and the scope of the invention.

Having thus set forth the nature of this invention, what is claimedherein is:

1. An improved automatic work steering mechanism for a sewing machinehaving a frame, a work supporting surface on the frame for a work piece,means mounted in the frame for forming stitches in the work piece, workfeeding means including a feed wheel, means for mounting the wheel onthe frame for hearing against the work piece, said mounting meansincluding means permitting the axis of said feed wheel to be moved whileretaining its relationship to the plane of said work supporting surface,and means for imparting rotation to the feed wheel to move the workpiece across the work supporting surface of the sewing machine, saidimproved automatic work steering mechanism comprising a servomechanism,means connecting the servomechanism to said feed wheel mounting meansfor moving the axis of the feed wheel, and means connected to theservomechanism for sensing the edge of the work piece to signal theservomechanism when the edge of the work piece deviates from apredetermined line of feed so that the servomechanism can operate themeans for moving the aXis of the feed wheel to feed the work piece backonto the line of feed.

2. The improved automatic work steering mechanism of claim 1 in whichthe means for mounting the feed wheel in the frame is a presser bar andthere is a pivotal connection between the feed wheel and the presser barfor moving the axis of the feed wheel.

3. The improved automatic work steering mechanism of claim 2 in whichthe pivotal connection between the feed wheel and the presser bar is asubstantially horizontal arcuate slideway and slide block.

4. The improved automatic work steering mechanism of claim 1 in whichthe means for sensing the edge of the work piece includes meansconnected to the servomechanism for signaling operation of theservomechanism, a sensing foot for contacting the edge of the workpiece,

and means for connecting the sensing foot to the means for signalingoperation of the servomechanism.

5. The improved automatic work steering mechanism of claim 4 in whichthe means for signaling operation of the servomechanism includes anamplifier connected to the servomechanism and a controlled potentiometerconnected between the amplifier and the means for connecting the sensingfoot to the means for signaling operation of the servomechanism.

6. The improved automatic work steering mechanism of claim 5 in whichthe means for connecting the sensing foot to the means for signalingoperation of the servomechanism includes a crank arm on the controlledpotentiometer and link means between the crank arm and the sensing foot.

7. The improved automatic work steering mechanism of claim 6 in whichthe link means includes sliding means so that the sensing foot can bemoved away from the work supporting surface of the frame.

8. The improved automatic work steering mechanism of claim 7 whichincludes means for biasing the sensing foot against the edge of the workpiece.

References Cited UNITED STATES PATENTS 2,678,010 5/1954 Pinkross112--214 2,979,745 4/1961 Schaefer et a1 69-l6 X 2,970,557 2/1961 Schwabet al. 112210 3,034,781 5/1962 Touchman et al. 112214 3,080,836 3/ 196 3Clemens et a1.

3,417,718 12/1968 Anderson 112-203 ALFRED R. GUEST,

US. Cl. X.R.

Primary Examiner

